#include <stdio.h>
#include <math.h>


int main()
{
    int i,count;
    printf("There are invertable primes with 4 digits:\n");
    for(count = 0,i = 1001;i < 9999;i += 2)
    {
        if(num(i))
        {
            printf(count%9?"%3d:%d":"%3d:%d\n",++count,i);
        }
    }
    return 0;
}
num(int number)
{
    int j,i;
    if(!ok(number)) return(0);
    for(i = number,j = 0;i > 0;i /= 10)
    {
        j = j*10+i%10;
    }
    if(number < j)
    {
        if(!ok(j)) return (0);
        else return(1);
    }else return(0);
}
ok (int number)
{
    int i,j;
    if(number%2 == 0) return(0);
    j = sqrt((double)number) + 1;
    for(i = 3;i <= j;i += 2)
    {
        if(number%i == 0) return(0);
    }
    return(1);
}
//熊贤豪